HX-4 is one of the twenty systems charted by Taisa Hanako while she commanded the YSS Elfin Princess in YE 30.

There is a small, unidentified military spaceport here.

• Type M5 V Red Dwarf
• Radius 2.30 x 10⁵ km (0.33 x sol)
• Mass 3.38 x 10²⁹ kg (0.17 x sol)
• Temperature 2600 K
• Luminosity 1.35 x 10²⁵ W (0.04 x sol)

• Type Rock Planet
• Orbital Radius 1.76 x 10⁷ km (0.12 AU)
• Period 8.54 x 10² hours (0.10 earth years)
• Gravity 2.63 m/s² (0.27 x earth)

• Type Terrestrial World
• Orbital Radius 3.32 x 10⁷ km (0.22 AU)
• Period 2.21 x 10³ hours (0.25 earth years)
• Physics Standard iron/silicate
• Hydrosphere 50 % water, 43 % ice
• Atmosphere Thin toxic
• Biosphere Prokaryotic microbes
• Civilization Military Spaceport
• Special Planetary rings

• Type Asteroid Belt
• Orbital Radius 4.41 x 10⁷ km (0.29 AU)
• Period 3.39 x 10³ hours (0.39 earth years)

• Type Rock Planet
• Orbital Radius 7.53 x 10⁷ km (0.50 AU)
• Period 7.57 x 10³ hours (0.87 earth years)
• Gravity 10.72 m/s² (1.10 x earth)
• Special Heavy radiation, large moon

• Type Asteroid Belt
• Orbital Radius 1.26 x 10⁸ km (0.84 AU)
• Period 1.64 x 10⁴ hours (1.88 earth years)

• Type Jovian Planet
• Orbital Radius 2.54 x 10⁸ km (1.70 AU)
• Period 4.68 x 10⁴ hours (5.36 earth years)
• Gravity 5.46 m/s² (0.56 x earth)
• Special Planetary rings, 47 small moons

HX-4 II

• Type Standard iron/silicate
• Radius 6990.56 km (1.10 x earth)
• Surface Area 6.14 x 10⁸ km²
• Land Area 3.13 x 10⁸ km² (2.10 x earth)
• Mass 8.24 x 10²⁴ kg (1.38 x earth)
• Density 5.76 g/cm³ (1.04 x earth)
• Composition 31.2% iron, 25.7% oxygen, 16.8% silicon, 16.2% nickel, 10.2% other metals, trace other elements

• Gravity 11.21 m/s² (1.15 x earth)
• Escape Velocity 12.52 km/s
• Rotation
• Period 28.29 hours
• Axis Tilt 12.10 °

• Water 50 %
• Ice 43 %

• Type Thin toxic
• Pressure 51.20 kPa (0.51 x earth)
• Composition 82.6% carbon dioxide, 17.4% oxygen, trace other gases

• Type Cold
• Min Temp 148 K (-125 °C)
• Avg Temp 280 K (6 °C)
• Max Temp 356 K (82 °C)

• Chemistry Carbon
• Lifeforms Prokaryotic microbes

• Type Military Spaceport
• Population 136
• Tech Level Interplanetary (nuclear fusion, space colonies, nanotechnology)
• Special Features Planetary rings